Starter jaw actuating device



Oct. 16, 1951 s. GILBERT 2,571,231

v STARTER JAW ACTUATING DEVICE Filed Sept. 29, 1949 2 Sheets-Sheet l INVEN TOR.

SAMUEL A LEE/PT S. GILBERT STARTER JAW ACTUATING DEVICE Oct. 16, 1951Filed Sept: 29, 1949 2 Sheets-Sheet 2 I o co LL T Q Q k} a m I roll v- 3N /(0 8 I a l I l INVENTOR.

SAMUEL 4 LBERT Patented Oct. 16, 1951 STARTER JAW ACTUATING DEVICESamuel Gilbert, Cedar Grove, N. J., assignor to Bendix AviationCorporation, Teterboro, N. J., a corporation of Delaware ApplicationSeptember 29, 1949,"Serial No. 118,64

6 Claims. (Cl. 74.-7)

The present invention relates to engine starters and particularly toengine starter meshing mechanism.

In engine starters usually some means arenecessary for engaging thestarter jaw with the engine to be started. One method used is to fric-{.4

tionally hold the starter jaws to cause axial movement thereof. Thismethod has numerous disadvantages in that the friction means are presentduring the operation of the starter. Also for very cold starts, thefriction means are not sufiicient to cause the necessary axial movementof the starter jaws.

It is an object of the present invention to provide an improved meshingmechanism that will avoid the above difficulties.

Another object of the invention is to provide an improved starter havinghigh axial torque on the starter jaws during the meshing period.

/ A further object of the invention is to provide an improved starter.

A further object is to provide an improved starter for operation at lowtemperatures.

The above and other objects and features of the invention will appearmore fully hereinafter from a consideration of the following descriptiontaken in connection with the accompanying drawings wherein oneembodiment of the invention is illustrated by way of example.

In the drawing:

Figure l is a sectional view of an engine starter embodying one form ofthe invention.

Figure 2 is a detailed view of one embodiment of the meshing mechanism.

Figure 3 is a detailed View of another embodiment of the meshingmechanism.

Referring to the drawing, the device therein shown comprises a starterassembly including, in general, a motor I having a driving shaftZrotatably supported by a bearing 3 mounted in end wall 3 of motorhousing 5. A pinion 6, shown as integral with the shaft 2 meshes withplanet gears 7. The planet gears I are rotatably supported by ballbearings 8 mounted on stub shafts 9 carried by spider cage ID. Theplanet gears mesh with a ring gear shown as integral with gear housingl2. The gear housing I2 is secured to the motor housing 5 by studs l3and nuts M as shown or by other suitable means.

Integral with the spider cage I is a pinion gear l adapted to engageplanet gears i6 which also engage the ring gear II. The gears l6 aresupported by bearings I! mounted on stub shafts l8 carried by a drummember I9. The drum member or barrel I9 is rotatably mounted in thehousing l2 by bearing 20.

The barrel I 9 is connected for the transmission of -rotary motion toaxially stationary spline nut 2| through a torque limiting disc pack 22.The disc pack 22 comprises a plurality of friction discs alternatelysplined to the inner face of the barrel i9 and the outer face of thespline nut 2|. The discs of the pack 22 are forced into frictionalengagement with each other by a plurality of circumferentially spacedsprings 23 compressed between a fiange 24 on the spline nut 2| and an 1adjustable nut 25 threaded into the barrel l9 and set so thatthe discpack 22 will slip at a predetermined torque.

The long lead internal threads of the spline nut 2| mesh with matingthreads of screw shaft 26 which is' connected to starter jaw 21 by axialsplines 28 for rotation therewith.

The present invention provides novel means for actuating the starter jaw21 into engagement with a crank shaft 29 or extension thereof of theengine to be started.

The pinion gear l5 has a shaft 30 extendin axially therefrom into thebarrel l9 and journaled by bearings 3| and 32 engaging enlarged sections33 and 34 respectively of shaft 30. The bearings 3| and 32 are supportedby an axially projecting inner drum member 35 of the barrel 19. Theshaft3|l terminates in an externally helicallygrooved screw section 36.The pitch of the threads of the screw section is less than that of thescrew shaft 26 and spline nut 2|.

' retained in the holes 4| by peening the holes 4| or in any othersuitable manner. Springs 42 urge the balls into engagement with thethreaded portion 36. The springs 42 are held in placeby screw caps 43inserted in the holes 4|. 'A spring 44 coacts between the flange 38 ofthe mesh rod suitable manner.

31 and a spring retaining ring 45. The retaining ring 45 is held in thescrew shaft 26 by a split ring 46 fitted in a groove 41 in the shaft2'6;

An oil seal 48 surrounds theouter circumfer-.

ence of the clutch jaw 21 and is held in position by a bracket 49clampedbetween a flange 50 on the gearhousing I2 and the engine crank case 5|by means of studs 52 and nuts 53 or any other In operation, when themotor I is energized rotary motion is imparted to the barrel by means ofthe planetary gear system which includes the pinion 15. The shaft 30being integral with the pinion l5 rotates therewith. The helicalthreaded portion 36 coacts with the balls 40 providing a screw likeaction that causes the mesh rod 31 to move axially to actuate thestarter jaw 21 and screw shaft 26 into operative position. Inasmuch asthe speed of rotation of the shaft 30 is greater than that of the barrelIS, the jaw 21 is moved axially to it engaging position with arelatively small amount of rotation of the barrel 19. The flange 38 ofthe mesh rod 31 coacts with a flange on the screw shaft 26 so that asthe mesh rod 31 is moved axially toward the engine engaging position,the screw shaft 26 is also moved axially. The pitch of the long leadsplines between the spline nut 2 l and the screw shaft 26 is such thatthe force exerted by the meshing rod in the axial direction moves thescrew shaft 26 axially relative to the nut 2|. Upon the starter jaw 21reaching operative position, the balls 40 will have passed the end ofthe shaft 30 and are out of mesh with the threaded portion 36 therebyallowing free rotation while cranking the engine. Should the jaws abutbefore meshing the springs 42 will yield and permit the balls 40 toratchet over the threads 36. Also any undue resistance to axial movementof the starter jaw 21 will cause the balls 40 to ratchet over thethreads 36. When the jaw 21 is in the retracted position, as shown, theballs 40 prevent the jaw 21 from being moved into engagement byvibration.

Referring now to Figure 3 for a modification of the structureillustrated in Figure 1, wherein a cylindrical mesh rod 50 is secured tothe starter jaw 21 by a nut 21a. The rod 50 has a shoulder portion 5|adapted to cooperate with the spring 44 to urge the jaw 21 intoengagement with the engine jaw 29. The end of the mesh rod 50 away fromthe jaw 21 has a counterbore 52 concentric with the shaft 30. Thecounterbore 52 has a threaded portion 53 adapted to mate with thethreaded portion 36. The remaining part of the counterbore 52 isrelieved for clearance for the threaded portion 36. In order to provideflexibility of the threaded portion 53 the mesh rod 50 which is springsteel has a plurality of longitudinal slots 54 extending the length ofthe counterbore 52.

In this embodiment, the shoulder 34 and bearing 32 are omitted, thethreaded portion 36 of the shaft 30 being formed adjacent to theshoulder 33. The operation is similar to that described for Figure 1.The threaded portion 36 coacts with the mating threads 53 in the meshrod 50 and drives the jaw 21 into engagement. The longitudinal slotspermit the threads 53 to ratchet over the threads 36 should the jaw abutbefore engagement. In the engaged position, the threads 53 are beyondthe threads 36 thus permitting free rotation of the starter jaw 21.

Inasmuch as the speed of rotation of the shaft 30 is greater than thatof the barrel [9, the jaw 21 is moved axially to its engaging positionwith a relatively small amount of rotation of the barrel.

Thus the disadvantages of a friction ring normally used to provide axialmovement of the starter jaw are overcome and a positive drive providedwhich insures meshing, even on cold starts and also retains the jaw inits retracted position when the engine is running.

Although only two embodiments of the invention have been illustrated anddescribed, various changes in the form and relative arrangement of theparts, which will now appear to those skilled in the art, may be madewithout departing from the scope of the invention.

What is claimed is:

- 1. In an engine starter, the combination of an assembly comprising anaxially stationary rotatable spline nut, a screw shaft in said nut, astarter jaw member adapted for rotation with and axial movement relativeto said screw shaft, means including a positive driven helical screw foractuating said starter jaw axially to an engine engaging position,yieldable means for drivably connecting said helical screw to saidstarter jaw, said last means being adapted to yield and release saidconnection when the opposition to axial movement of said starter jawexceeds a predetermined maximum.

2. For use in an engine starter, the combination of an assemblycomprising an axially stationary rotatable spline nut, a screw shaftconnected for rotation with and axial movement relative to said splinenut, a starter jaw adapted for rotation with and axial movement relativeto said screw shaft, a jaw retaining member extending into and having ashoulder adapted to engage said screw shaft, means including anexternally threaded shaft for coacting with said jaw retaining memberfor driving said member axially to an engine engaging position, said jawretaining member having ball receiving openings at spaced intervalsalong a helical path corresponding in pitch to the pitch of saidexternally threaded shaft, balls positioned in said openings and springmeans for resiliently biasing said balls into engagement with saidexternally threaded shaft.

3. For use in an engine starter, the combination of an assemblycomprising an axially stationary rotatable spline nut, a screw shaftconnested for rotation with and axial movement relative to said splinenut, a starter jaw adapted for rotation with and axial movement relativeto said screw shaft, a jaw retaining member extending into and having ashoulder adapted to engage said screw shaft, means including anexternally threaded shaft for coacting with said jaw retaining memberfor driving said member axially to an engine engaging position, said jawretaining member having a yieldable internally threaded portion adaptedto engage said externally threaded shaft and to ratchet over saidexternally threaded shaft upon abutment of said starter jaw.

4. In an engine starter, the combination of an assembly comprisingrotatable driving means, an axially stationary rotatable spline nut, aplanet gear assembly for connecting said spline nut to said drivingmeans, a screw shaft interposed in said splined nut and having matingsplines thereon, a starter jaw member splined to said screw shaft forrotation with and axial movement relative to said screw shaft, a jawretaining member having a circumferential flange extending into saidscrew shaft, means including a helically threaded member rotatablyconnected to' said driving means, helical means secured to said flangeand adapted to coact with said threaded member to translate rotarymotion to lateral motion to move said starter jaw axially to an engineengaging position, said last means being yieldable to permit ratchetingof said threaded abutment of said starter jaw.

5. For iise in an engine starter, a starter jaw actuating mechanismcomprising, in combination, a starter jaw to be actuated, a jawretaining member securely attached to said starter jaw at one endthereof, said jaw retaining member having a counterbore at the otherend, a shaft member concentric with said counterbore, said shaft memberand said counterbore having mating parts adapted to coact to form a jackscrew for actuating said starter jaw axially to an engine startingposition, one of said coacting parts being yieldable to permitratcheting when said starter jaw reaches said engine starting position.

6. In an engine starter having a starter jaw adapted to move axially toengine engaging position upon energization of said starter, thecombination comprising an axially stationary rotatable spline nut, ascrew shaft connected for rotation with and axial movement relative tosaid spline nut, a starter jaw adapted for rotation with and axialmovement relative to said screw shaft, a jaw retaining member securelyattached to said starter jaw and having a counterbored portion extendinginto said screw shaft, spring 6 means for yieldably biasing said screwshaft and said jaw retaining member against relative axial movement, ashaft having a helical externally threaded portion concentric with saidcounterborecl portion, said counterbored section having an internalthreaded portion adapted to mesh with said externally threaded portiontomove said jaw retaining member axially upon rotation of said shaft,said jaw retaining member cooperating with said screw shaft to move saidstarter jaw to an engine engaging position, and means including aplurality of axial slits in said counterbored portion to permitratcheting of said threaded portions when opposition to said axialmovement exceeds a predetermined value.

SAMUEL GILBERT.

REFERENCES CITED FOREIGN PATENTS Country Date Germany Feb. 22, 1919Number

